While USDA has monitored crops around the world for almost a century, the discovery that satellites can “see” greening of vegetation has revolutionized agricultural monitoring for food security. The development of the GLAM system in the 1980s, a collaboration with USDA and the International Production Assessment Division, has helped governments to assess whether or not there will be enough basic food crops to feed their populations, as well as provide international food aid organizations with a tool to predict where food shortages might occur.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0